<template>
  <div class="s-canvas">
    <canvas id="s-canvas" style="padding:0px;" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
export default {
  name: "SIdentify",
  props: {
    identifyCode: {
      type: String,
      default: "7869",
    },
  },
  data() {
    return {
      fontSizeMin: 20,
      fontSizeMax: 25,
      backgroundColorMin: 180,
      backgroundColorMax: 240,
      colorMin: 50,
      colorMax: 100,
      lineColorMin: 30,
      lineColorMax: 60,
      dotColorMin: 20,
      dotColorMax: 255,
      contentWidth: 90,
      contentHeight: 32,
    };
  },
  methods: {
    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      let r = this.randomNum(min, max);
      let g = this.randomNum(min, max);
      let b = this.randomNum(min, max);
      return "rgb(" + r + "," + g + "," + b + ")";
    },
    drawPic() {
      let canvas = document.getElementById("s-canvas");
      let ctx = canvas.getContext("2d");
      // ctx.textBaseline = 'bottom'
      // 绘制背景
      ctx.fillStyle = this.randomColor(
        this.backgroundColorMin,
        this.backgroundColorMax
      ); //图形填充颜色设置
      ctx.strokeStyle = this.randomColor(
        this.backgroundColorMin,
        this.backgroundColorMax
      ); //图形轮廓的颜色设置
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight); //绘制一个填充的矩形 0 0 width height x起点 y起点  宽 高
      ctx.strokeRect(0, 0, this.contentWidth, this.contentHeight); // 绘制一个矩形边框 0 0 width height x起点 y起点  宽 高
      // ctx.clearRect(50,0,this.contentWidth,this.contentHeight)  //清除指定矩形区域，清除部分完全透明
      // 绘制文字
      for (let i = 0; i < this.identifyCode.length; i++) {
        this.drawText(ctx, this.identifyCode[i], i);
      }
      this.drawLine(ctx);
      this.drawDot(ctx);
    },
    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
      ctx.font =
        this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei"; //字体大小
      ctx.textBaseline = "alphabetic"; //基线对齐
      let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 2));
      let y = this.randomNum(this.fontSizeMax, this.contentHeight - 2);
      var deg = this.randomNum(-45, 45);
      // 修改坐标原点和旋转角度
      ctx.translate(x, y); //移动不同位置  参数偏移量
      ctx.rotate((deg * Math.PI) / 180); //旋转 参数角度
      ctx.fillText(txt, 0, 0);
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 180);
      ctx.translate(-x, -y);
    },
    drawLine(ctx) {
      // 绘制干扰线
      for (let i = 0; i < 8; i++) {
        ctx.strokeStyle = this.randomColor(
          this.lineColorMin,
          this.lineColorMax
        );
        ctx.beginPath(); //新建一条路径
        ctx.moveTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        ); //设置起点x,y
        ctx.lineTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        ); //绘制直线 x,y 一条当前位置到x,y点的直线
        ctx.stroke(); // 通过线条绘制图形轮廓
        // ctx.closePath() //结束闭合路径
      }
    },
    // drawDot(ctx) {
    //   // 绘制干扰点
    //   for (let i = 0; i < 100; i++) {
    //     ctx.fillStyle = this.randomColor(0, 255);
    //     ctx.beginPath();
    //     // 绘制圆弧或圆，x,y,radius，startAngle,endAngle,anticlockwise // x,y 圆心点，radius 半径，从startAngle开始到endAngle结束
    //     ctx.arc(
    //       this.randomNum(0, this.contentWidth),
    //       this.randomNum(0, this.contentHeight),
    //       1,
    //       0,
    //       2 * Math.PI
    //     );
    //     ctx.fill(); //通过填充路径的内容区域生成实心的图形。
    //   }
    // },
  },
  watch: {
    identifyCode() {
      this.drawPic();
    },
  },
  mounted() {
    this.drawPic();
  },
};
</script>

